Generate license.xml THREESCALE-170

[hallelujah]

Part of https://issues.jboss.org/browse/THREESCALE-170
We need to generate a licenses.xml for packages installed.
I think that it should be the same as apicast as it is using apicast as base image.

TODO:

• A plugin for Lua packages to be written for licenses-finder

[andrewdavidmackenzie]

We need to get this done before we tag for Er2....

[mikz]

This has no extra dependencies over APIcast, so it is going to inherit it. No need to do anything.